Friday 8th July 2011

OPERATIONAL ISSUES IN RADIOACTIVE WASTE MANAGEMENT AND NUCLEAR DECOMMISSIONINGSession 7: Waste Management

Presented by

Vince Cane – Senior Radioactive Waste Management Eng ineerSerco Defence, Science and Nuclear – JRC Ispra

Radioactive Waste Treatment and Conditioning

Introduction

� Treatment and Conditioning in the Context of Decommissioning

� Definitions

Radioactive Waste Treatment and Conditioning

� Radioactive Waste Treatment

� Radioactive Waste Conditioning

� Summary

� Acknowledgements

RADIOACTIVE WASTE TREATMENT & CONDITIONING

IN THE CONTEXT OF IN THE CONTEXT OF DECOMMISSIONING

Decommissioning & Radioactive Waste ManagementThe Typical Decommissioning Model

FROM TOFROM

THIS…

TO

THIS…

Decommissioning Objectives – The ‘End Game’

1. Fully Discharge All Financial Liabilities

2. Leave No Future Detriment (Sustainability Principle)

3. Apply a ‘Waste Hierarchy’

4. Discharge Liabilities Responsibly and Effectively

5. Minimise the ‘Consumption’ of Valuable Radioactive Waste Disposal Facilities

Application of a Waste Hierarchy*

� Objectives

– Segregate ‘at source’ as much material as possible to minimise quantities of radioactive waste

– Clear or exempt as much material as possiblepossible

– Decontaminate and recycle as much radioactive waste as possible (e.g. metals and concrete)

– Reduce volumes of radioactive waste wherever possible prior to conditioning

– Minimise volumes of radioactive waste sent for disposal

*European Directive 2008/98/EC (Waste Framework Directive)

Image courtesy of LLW Repository Ltd, United Kingdom

The Liability Discharge Process – From A to B

It is important to see the ‘Big Picture’

The Decommissioning & Waste Management Process

A:

The Nuclear

Liability

B:

Liability

Discharge

Treatment and Conditioning in ContextRADIOACTIVE

WASTE

MANAGEMENT

4.

DISPOSAL

MANAGEMENT

PRE-DISPOSAL

MANAGEMENT

WS-G-2.5

1.

PROCESSING

2.

STORAGE

3.

TRANSPORT

Derived from IAEA Safety Glossary, Terminology used in nuclear safety and radiation protection, 2007 edition

MANAGEMENT

PRE-TREATMENT CONDITIONINGTREATMENT

COLLECTION

SEGREGATION

CHEMICAL

ADJUSTMENT

DECONTAMINATION

ACTIVITY REMOVAL/

REDUCTION

CHANGE OF

COMPOSITION

VOLUME

REDUCTION

IMMOBILISATION

PACKAGING

OVERPACKING

TREATABLE

WASTENON-TREATABLE WASTE

DEFINITIONSDEFINITIONS

Definitions of ‘Treatment’ & ‘Conditioning’ *

� Treatment

– Operations intended to benefit safety and/or economy by changing the characteristics of the waste. Three basic treatment objectives are:

� (a) Volume reduction;

� (b) Removal of radionuclides from the waste (or reduction);

� (c) Change of composition.� (c) Change of composition.

– Treatment may result in an appropriate waste form. If treatment does not result in an appropriate waste form, the waste may be immobilized.

� Conditioning

– Those operations that produce a waste package suitable for handling, transport, storage and/or disposal. Conditioning may include the conversion of the waste to a solid waste form, enclosure of the waste in containers and, if necessary, provision of an overpack.

*IAEA Safety Glossary, Terminology used in nuclear safety and radiation protection, 2007 edition

Some Other Useful Definitions*

� Immobilisation

– Conversion of waste into a waste form by solidification, embedding or encapsulation. Immobilisation reduces the potential for migration or dispersion of radionuclides during handling, transport, storage and/or disposal.

� Segregation (pre -treatment)� Segregation (pre -treatment)

– An activity where types of waste or material (radioactive or exempt) are separated or are kept separate on the basis of radiological, chemical and/or physical properties, to facilitate waste handling and/or processing.

� Waste Form

– Waste in its physical and chemical form after treatment and/or conditioning (resulting in a solid product) prior to packaging. The waste form is a component of the waste package.

*IAEA Safety Glossary, Terminology used in nuclear safety and radiation protection, 2007 edition

Waste, Waste Container, Waste Form, Waste Package

‘TREATED’ WASTE ITEMS

WASTE CONTAINER

E.G. CP-5.2

Empty

Container

Container

Loaded with

Waste

Definition:

WASTE

CONTAINER

PRODUCTION

PROCESS

Design &

manufacturing

records

Waste

inventory

QUALITY

ASSURANCE

IMMOBILISATION MATERIALS

WASTE CONTAINER ‘FURNITURE’

WATER

Waste

Loaded

Container

with Furniture

Immobilized

Final waste

Package

Definition:

WASTEFORM

Definition:

WASTE

PACKAGESAND CEMENT FILLER

inventory

Design &

manufacturing

records

Materials &

production

records

RADIOACTIVE RADIOACTIVE WASTE

TREATMENT

Waste Treatment

RADIOACTIVE

WASTE

MANAGEMENT

4.

DISPOSAL

PRE-DISPOSAL

MANAGEMENT

1. 2. 3.DISPOSAL

MANAGEMENTPROCESSING STORAGE TRANSPORT

PRE-TREATMENT CONDITIONINGTREATMENT

COLLECTION

SEGREGATION

CHEMICAL

ADJUSTMENT

DECONTAMINATION

ACTIVITY REMOVAL/

REDUCTION

CHANGE OF

COMPOSITION

VOLUME

REDUCTION

IMMOBILISATION

PACKAGING

OVERPACKING

TREATABLE

WASTENON-TREATABLE WASTE

Waste Treatment

� Operations intended to benefit safety and/or economy by changing the characteristics of the waste

– Volume reduction through techniques such as size reduction, supercompaction, incineration or high temperature processes etc.

– Removal or reduction of radionuclide inventories through decontamination, ion exchange, filtration/segregation, evaporation etc.decontamination, ion exchange, filtration/segregation, evaporation etc.

� Note: Careful assessment on a case by case basis is needed to ensure that a net benefit can be achieved. Secondary wastes can be more problematic than the primary waste…

– Change of composition through techniques such as high temperature processes, incineration, precipitation, flocculation etc.

– Note that many techniques can achieve a combination of benefits.

� Size reduction of waste items can be used effectively to optimise package loading and increase waste density. There are many available techniques including cold cutting, hot cutting, shearing, cropping, sawing, laser cutting, nibbling etc. Many of these techniques can be applied remotely if required.

Volume Reduction – Size Reduction

Volume Reduction - Supercompaction

� Volume Reduction by Supercompaction. Typically a 1000 to 2000 Tonne hydraulic press is used to vertically compress a 220L drum into a ‘puck’. Volume reduction factors of up to 5 are typical.

Volume Reduction - Incineration

� Incineration is a very effective method for achieving volume reduction factors of up to 20. In keeping with the waste hierarchy it also offers the possibility of energy recovery from waste. Resultant ashes can be supercompacted or immobilised by solidification. Abatement systems are critical to control and limit discharges to the environment and these may result in secondary wastes.

� Specific to metals

� Results in recycling of up to 95% of original material

� Radioactivity is concentrated in furnace slag and usually returned to the originating site as radioactive waste (<5% of original volume)

Volume Reduction – Metal Melting

� Recovered metals are conventionally recycled

Radioactivity Reduction - Decontamination

� There are many different forms of decontamination technique and many processes utilise more than one technique. Selection of the right techniques depends on the substrate and the type of contamination encountered.

� Decontamination techniques generally fall into either ‘wet’ or ‘dry’ classifications. They include; concrete scabbling, shaving, planing, diamond wire slicing, high pressure and ultra high pressure water diamond wire slicing, high pressure and ultra high pressure water jetting, dry ice blasting, abrasive blasting, bead blasting, ultrasonic bath, chemical treatment (acidic and/or chelating agents are common), strippable coatings (spray on or paint on), ice pigging, laser scabbling etc…

� Decontamination generally results in the production of a secondary waste and consideration of downstream treatment and conditioning of this waste must be a key consideration in selecting a technique.

� Generally beneficial where short half-life radionuclides dominate the inventory of a waste type (e.g. 60Co activation products in steel alloys)

� Employed extensively to support deferred decommissioning programmes (e.g. Magnox ‘Safestore’ philosophy in UK)

� This technique results in a genuine reduction in radioactive inventories

Radioactivity Reduction – Decay Storage

� This technique results in a genuine reduction in radioactive inventories and is entirely consistent with the philosophy of waste hierarchy

� Waste can be stored in-situ (i.e. safestore) or in appropriate shielded containers (e.g. Mosaik® casks)

Waste Conversion

� Waste conversion can beneficially alter the composition of wastes and may also result in immobilisation/passivation, meaning that further conditioning is not required. Techniques include wet oxidation, plasma, vitrification, cold crucible melting, steam reforming, precipitation, flocculation, dissolution etc. These techniques are particularly suited to wastes that are not directly suitable for conditioning (for example ion exchange and organic materials).exchange and organic materials).

RADIOACTIVE RADIOACTIVE WASTE

CONDITIONING

Waste Conditioning

RADIOACTIVE

WASTE

MANAGEMENT

4.

DISPOSAL

PRE-DISPOSAL

MANAGEMENT

1. 2. 3.DISPOSAL

MANAGEMENTPROCESSING STORAGE TRANSPORT

PRE-TREATMENT CONDITIONINGTREATMENT

COLLECTION

SEGREGATION

CHEMICAL

ADJUSTMENT

DECONTAMINATION

ACTIVITY REMOVAL/

REDUCTION

CHANGE OF

COMPOSITION

VOLUME

REDUCTION

IMMOBILISATION

PACKAGING

OVERPACKING

TREATABLE

WASTENON-TREATABLE WASTE

Waste Conditioning - Encapsulation

� Encapsulation is the process of immobilising solid waste by application of a fluidic matrix (often cement based) that fully penetrates the waste and cures to form a solid monolith

Waste Conditioning - Embedding

� Embedding (or entombment) is the process of immobilising solid waste by placing items into a container and filling the void with a fluidic matrix (again cement is common) that cures to form a solid monolith.

� Generally used for immobilising containers or larger waste items

Waste Conditioning - Solidification

� Solidification is the process of immobilising ‘mobile’ waste by adding a quantity of waste to a container and mixing with, typically, cement, fillers and water. A ‘lost paddle’ is used to homogenise the mix and it cures in a similar manner to encapsulation to form a solid monolith

Waste Conditioning - Vitrification

� Vitrification is the process of immobilising liquid (typically HLW) waste by melting a quantity of waste with glass formers to produce a very high integrity solid monolith. High integrity stainless steel bottles are used for storage and ultimate disposal.

Waste Conditioning – Robust Container

� In some instances it is possible to validate waste packaging without the use of immobilisation, generally where a very robust, thick walled container is utilised and all potential waste degradation mechanisms have been mitigated (e.g. by drying of sludges) to achieve a passive state.

� Overpack*: A secondary (or additional) outer container for one or more waste packages, used for handling, transport, storage and/or disposal.

� Overpacking is commonly used for the packaging of spent nuclear fuel but can also be used for interim management of conditioned waste packages.

Waste Conditioning – Overpacking

*IAEA Safety Glossary, Terminology used in nuclear safety and radiation protection, 2007 edition

Summary

� A wide range of proven and established techniques for treatment and conditioning of many types of radioactive waste are available today.

� Wastes and approaches to waste management across different countries are generally consistent and therefore transferable, presenting excellent opportunities for optimisation of programmes.

� It is essential to understand and apply compliance requirements for � It is essential to understand and apply compliance requirements for disposal from the outset of decommissioning projects. These requirements vary from country to country but follow the same general themes.

� Treatment and conditioning choices must be made as part of a fully holistic consideration of decommissioning and waste management strategy.

� The Waste Hierarchy should be applied holistically

Acknowledgements

I would like to acknowledge the following, whose information has been utilised in preparing this presentation;

– Belgoprocess, Belgium– COVRA, Netherlands– Fonteijne Grotnes, Netherlands– Fox Broadcasting Company, Springfields NPP– GNS, Gesellschaft für Nuklear-Service, Germany– International Atomic Energy Agency, Vienna– JMC Recycling Systems Ltd, United Kingdom– JMC Recycling Systems Ltd, United Kingdom– LLW Repository Ltd, United Kingdom– Magnox Ltd, United Kingdom– NDA Radioactive Waste Management Directorate, United Kingdom– Nuclear Decommissioning Authority, United Kingdom– Nuclear Decontamination Services Ltd, United Kingdom– Ontario Power Generation, Canada– Sellafield Ltd, United Kingdom– Studsvik AB, Sweden– The Welding Institute, United Kingdom– Trumpf Gruppe, Germany– Vincent Van Gogh, Sunflowers

Thank YouThank You